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University of Ottawa *
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Material Science
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Dec 6, 2023
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docx
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THEME 7 – MINERALS
[ 38/38 : A+ ]
A
CTIVITY
7.2S – T
ECHNICAL
Q
UESTIONS
(
/38)
Reference material:
-
Lecture of associated theme (Brightspace)
-
Glossary (
https://mysite.science.uottawa.ca/dumas/
)
-
Reference documents “Sections of the lab manual” in Brightspace
Activities:
Activity 1 (
/9)
Link the classes of minerals of the left column to their basic anion in the center column, and then to an
example of this class of mineral in the right column.
Please use the following format for your answers:
mineral class, basic anion, example of mineral. For example: 1,A,i.
Mineral classes
Basic anions
Examples of minerals
1.
Oxides
(E, viii)
A.
SiO
4
4-
i.
Halite (NaCl)
2.
Carbonates
(C, vi)
B.
PO
4
3-
ii.
Olivine (Mg
2
SiO
4
)
3.
Sulfides
(G, iii)
C.
CO
3
2-
iii.
Pyrite (FeS
2
)
4.
Silicates
(A, ii)
D.
No anion
iv.
Copper (Cu)
5.
Hydroxides
(I, vii)
E.
O
2-
v.
Barite (BaSO
4
)
6.
Halides
(D, i)
F.
SO
4
2-
vi.
Calcite (CaCO
3
)
7.
Sulfates
(F, v)
G.
S
2-
vii.
Brucite (Mg[OH]
2
)
8.
Phosphates
(B, ix)
H.
Cl-, F-, Br-, I-
viii. Magnetite (Fe
3
O
4
)
9.
Native elements
(H, iv)
I.
OH
-
ix.
Apatite (Ca
5
[PO
4
]
3
[OH,Cl,F])
Activity 2 (
/29)
Answer the following questions.
1.
What are the five criteria that define a mineral? (
/5)
Solid, natural, inorganic, crystalline, fixed chemical composition
2.
Is glass a mineral? Why? (
/2)
No because its chemical composition is not always the same and it does not have a crystalline
structure.
3.
Which physical property, color or streak, is most reliable for identifying minerals? Explain your
answer. (
/2)
Streak because it cannot be affected by weathering like the outer colour of a mineral can be.
4.
What is the difference between a crystal face and a cleavage plane?
Hint: think about how each is
formed (what each results of).
(
/2)
A crystal plane is the “external expression of the internal atomic structure of a mineral” meaning it
has to do with how the mineral was formed on the atomic level. A cleavage plane is where a mineral
tends to break along certain lines within that atomic structure.
5.
What can be concluded from the crystal structure of minerals that have no cleavage? Give an
example of a mineral that does not have cleavage. (
/2)
The crystal structure of a mineral with no cleavage is very strong with no bonds being much weaker
than others. One mineral with no cleavage is Olivine.
6.
Circle the correct answer. The nail (or steel blade) can scratch: (
/1)
-Incorrect answers crossed out
a)
Quartz, feldspar, biotite
b)
Gypsum, feldspar, pyrite
c)
Talc, halite, calcite
Quartz and Feldspar cannot be scratched by the nail therefore the answer is (c).
7.
Describe the cleavage of
feldspars
. To do this, give the
number of cleavage directions
, the
angle
at
which they intersect, and the name of the associated
cleavage type
. (
/2)
-
Number of cleavage directions: 2
-
Angle at which they intersect: 90°
-
Cleavage type: Prismatic
8.
For the following minerals:
dark-colored plagioclase feldspar
,
pyroxene
, and
amphibole
: (
/6)
a)
Give 4 physical properties common to these three minerals.
o
White streak
o
Prismatic cleavage
o
Dark green/gray to black in colour
o
Hardness between 5 to 6
b)
Which property best distinguishes
amphibole
from
pyroxene
and
plagioclase feldspar
?
o
The angle of intersection of the cleavage is 60-120° as opposed to the other two which
are 90°
c)
Which property best distinguishes
pyroxene
from
plagioclase feldspar
?
o
Plagioclase Feldspar has polysynthetic twinning, Pyroxene has no twinning.
9.
Which property best distinguishes
biotite
from
muscovite
? (
/1)
The streak of biotite is light to dark brown whereas the streak of Muscovite is white.
10. Using the mineral identification tables, say which mineral corresponds to the description of the
following physical properties: non-metallic luster, dark (~ black), harder than glass, ~90° prismatic
cleavage, no twinning. (
/1)
Pyroxene
11. Give a utility for each mineral below. (
/5)
a)
Talc
o
Baby powder
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